Household dryer system



R. F. DOTY HOUSEHOLD DRYER SYSTEM Filed March 6, 1967 1/ p hilvl'zlflp/ ,2

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ATTORNEY United States Patent 3,399,461 HOUSEHOLD DRYER SYSTEM Roger F. Doty, Connersville, Ind., assignor to Philco- Ford Corporation, Philadelphia, Pa., a corporation of Delaware Filed Mar. 6, 1967, Ser. No. 620,693 8 Claims. (CI. 34-45) ABSTRACT OF THE DISCLOSURE A combination of programing and signalling means for a household dryer. The programing system is arranged to effect, after drying and normal cool-down, a sequence of signalling operations and a predetermined extension of the cool-down, to minimize wrinkling of fabrics in the dryer while avoiding excessive continuation of the cool-down.

BACKGROUND AND SUMMARY OF THE INVENTION 1. Field of the invention Automatic dryers for fabrics, and especially fabrics of the so-called permanently pressed type. In particular, the invention pertains to household machines for drying clothes and articles of laundry which tend to wrinkle if they come to rest in the dryer basket while they are hot or warm.

2. Description 09 the prior art The household dryers most commonly used up to now provided heat drying followed by a short cool-down, usually of about five minutes duration. This was suflicient to avoid safety hazards to the housewife when she removed the fabrics from the machine, but usually did not provide for cooling of the clothes for a time sufficient to avoid wrinkling, since the housewife does not always remove the very warm material promptly, upon the automatic termination of the cycle. In particular, deep-set wrinkles have been encountered in the so-called permanent press fabrics, where the drying and cool-down period often was followed by a period of time during which hot or warm fabrics were at rest in the dryer basket.

Other dryers have been arranged for a program including a cool-down of sufiicient duration, such as a total of ten minutes, to make sure that the fabrics, after heatdrying, are cooled almost down to room temperature. Such dryers prevent wrinkling effectively, even if the fabrics come to rest in the dryer basket on automatic termination of the cool-down tumbling operation. However, such dryers always use this operating cycle of considerable length, thereby forcing the housewife to tie up the dryer for a long total period of drying and cooling and to expend a substantial amount of electric power for the total dryer operation.

SUMMARY OF THE INVENTION The invention is directed to a laundry dryer having an improved drying cycle in combination with a unique dual alarm system for alerting the user when the fabric should be removed, if wrinkling is to be minimized. If the user fails to respond to a low-level alarm, which occurs at the end of'the normal cool-down period, the new dryer normally continues through a further extension of the cool-down period, and in any event a brief high-intensity alarm is sounded. Then or very shortly thereafter, with the clothes load near room temperature, the machine stops. If the high-intensity alarm is also ignored, wrinkling is still minimal because of the low clothes temperature then existing.

3,399,461 Patented Sept. 3, 1968 BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a front view of a preferred embodiment of the invention. FIGURE 2 is a circuit diagram of this embodiment, and FIGURE 3 is a block diagram, indicating the operation of the system incorporated in this em bodiment and circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENT The new clothes dryer 10 (FIGURE 1) has the usual door 11 for loading it with fabrics to be dried and for removing them in due course. As is also usual, the dryer has a timer control means 12, installed for instance on backsplash 13. This control is connected by cable 14 with signal apparatus, such as buzzer 15, for giving the new sequence of low-level and high-intensity alarms. Buzzer 15 may be situated on the machine or, if desired, it may be located remotely as shown in FIGURE 1.

In the preferred and illustrated system, control means 12 comprises a time switch TS (FIGURE 2), which provides the usual heater and motor circuit connections 1, 2, and in accordance with the invention also provides a plurality of signal circuit connections 3 and 4. The construction of the circuits can best be explained by describing their operation, which is as follows.

The initial or drying operation, which can be conventional, begins when the user loads the dryer with wet clothes and then closes its door 11 (FIGURE 1), thereby closing door switch 11-S (FIGURE 2). This establishes motor circuit L1, 2, M (S, R), NL, by well known operations of starting and running coils R, S in dryer motor M. As soon as the motor has established proper tumbling speed of dryer basket B, driven thereby, the system also starts heater H. It does this through circuit L1, 1, H, CS, L2, which includes the usual centrifugal switch CS in the motor. Time switch TS is operated by a timer motor TM, which is in parallel with dryer motor M. Accordingly the time switch is started together with motor M. It then allows the illustrated system to perform its well known heating and drying cycle, indicated by letter D, during which the clothes in basket B are tumbled, while the motor operates air blower A and thereby produces an air stream, heated by heater H to dry the tumbling clothes. The drawing indicates a simple system wherein the duration of the drying period is determined simply by the normal operation of time switch TS, controlling heater circuit 1. It will be understood that this switch can be preset, by suitable adjustment means (not shown), to provide for instance sixty minutes or eighty minutes drying time, depending mainly on the types of fabrics to be dried.

After such drying, the new machine begins its characteristic cool-down. For the moment it goes automatically into a normal phase N of this operation, as the time switch then interrupts heater current 1 while it keeps motors M, TM energized through circuit 2. Accordingly the clothes in basket B continue to tumble but are exposed to a cold air stream, provided by blower A. Time switch TS causes the normal cool-down to last a predetermined period, for instance the usual five minutes, whereafter removal of the clothes is safe, although not always desired. They are still hot or at least warm to the touch of the human hand, but are in condition to be handled manually without danger, and accordingly to be removed by the user, who can at this time fold them and either hang up for further drying or store them away.

As the clothes are still hot or warm, these clothes and especially those of permanent press type would wrinkle if they were brought to rest in the dryer basket upon the performance of the initial cool-down. This applies mainly to certain types of fabrics, increasingly used in recent times, which are often designated as permanent press fabrics. The new system protects them by continuing the cold-air tumbling of the warm clothes if the user does not remove the clothes, as described. The machine performs this further operation during a predetermined extension of the cool-down period, combined with a signalling operation which ensues upon the end of the normal cooldown N.

At the start of this extension or new cycle E, time switch TS causes buzzer to sound, or of course if preferred, additionally or alternatively causes some alram light to flash. It does this in such a way as to emit a relatively low level signal and thereby to indicate, with only moderate urgency and with minimum disturbance, that the housewife should remove the clothes. For these purposes time switch TS at this time connects energy source L1 through a first signal circuit 3, resistor 15R and buzzer 15 (in series with said resistor) to neutral line NL, whereupon buzzer 15 begins to emit its relatively subdued signal. No change occurs at this time in the motor circuit, so that there ensues further cold-air blowing and tumbling during period E, while low buzzing sound emanates from the buzzer. This continues, for instance seven minutes, unless the housewife ends it by attending the dryer, that is, by opening door switch 11-8 and thereby stopping the machine as she removes the clothes, in response to the signal.

The housewife is not always able at once to respond in this way, and promptly remove the clothes at the time of the low-level signal. Nor would it be possible in all cases then to enforce her action by using an alarm bell of higher sound level. On the contrary, for many households a single alarm is sometimes too loud for comfort and at other times too soft for reliability. However, remarkably improved operation ensues from the sequence of soft and loud signals combined with cool-down extension, as described herein.

Therefore, in further accordance with my invention, the Extended Cool-down period E is limited (that is, in the illustrated embodiment, timed) in such a way as to effect substantial temperature reduction, usually from warm to cool, or to a temperature only slightly above room tem perature. Desirably, still further cool-down extension period is then added, and there ensues a second signalling operation. Accordingly, if the clothes have still not been removed during the Extended Cool-down, there follows a Final Cool-down period P coupled with the giving of a new, stronger, and more readily perceived signal. For this latter purpose time switch TS then connects source L1 with buzzer 15 through the new circuit 4, which bypasses resistor 15R, while it continues to keep motors M, TM energized. The Final Cool-down may for instance last one minute.

If the user has ignored all signals, the machine automatically stops motor M, basket B and air blower A, by time switch TS, whereby the clothes-by then substantially down to room temperaturecome to rest in basket B. The ultimate result, obtained in this case, is generally similar to that of a long-extended or so-called ten minute cooldown of known type. It most effectively avoids wrinkling. However, the new system differs from those according to earlier types in that it facilitates avoiding any waste of time and of electric current, and also minimizes the use of disturbing signals. This is achieved by the new means for signalling with increasing urgency, while continuing to cool and tumble the fabrics in the dryer basket during an automatically started and manually terminable extension of the brief normal cool-down. Importantly the new system also differs from the old standard five minute cool-down unit, with or without signalling means, in that it protects the clothes more effectively against wrinkling. It does not attempt to force the user to respond to a signal that is either too loud to be comfortable or too soft to be reliable.

The new system achieves the improvements, described herein, by means of a single buzzer or the like, with extremely simple circuitry for the same and for the entire control system. The new cool-down and signalling operations are thus provided by simple, reliable and inexpensive control means.

While only a single embodiment of the invention has been fully described, the details thereof are not to be construed as limitative of the invention. The invention contemplates such variations and modifications as come within the scope of the appended claims.

I claim: 1. A household dryer of the type having means for heating and tumbling fabrics to dry them, said dryer comprising:

means providing for cooling and tumbling of the dried fabrics during a first predetermined cool-down period;

means for extending said cooling and tumbling during an added cool-down period, and for emitting a lowlevel signal during said added period; and

means for emitting a higher intensity signal as said extended period is concluded.

2. A dryer as described in claim 1 wherein the lastmentioned means is constructed and arranged also to provide further extension of said cooling and tumbling while the higher intensity signal is emitted.

3. A dryer as described in claim 1, including a control circuit which comprises a switch unit and an alarm device to emit said signals; said switch unit including parts of said cool-down system and cool-down extension means.

4. A dryer as described in claim 3 wherein said alarm device is part of said control circuit and said circuit and switch unit include two circuit branches for said alarm device, one to cause emission of the initial type of signal and the other to cause emission of the further type of signal.

5. A dryer as described in claim 4 wherein said one circuit branch includes a resistor.

6. A dryer as described in claim 3, wherein said switch unit is a time switch.

7. A dryer as described in claim 6, wherein said control circuit includes a first motor unit to effect tumbling of the fabrics and to effect air blowing for heating and later cooling them, and a second motor unit, in parallel with said first motor unit, to operate said time switch.

8. A dryer as described in claim 3 wherein said alarm device is mounted remotely of said switch unit.

References Cited UNITED STATES PATENTS 3,050,864 8/1962 Sasnett 3453 X 3,286,359 11/1966 Orr et al 34-53 X 3,293,769 12/1966 Graham 3445 3,365,809 1/1968 Eppley 3445 X FREDERICK L. MATTESON, JR., Primary Examiner. E. G. FAVORS, Assistant Examiner. 

